Thermodynamic Models for Determination of the Solubility of Sulfanilic Acid in Different Solvents at Temperatures from (278.15 to 328.15) K

Abstract

Data on corresponding solid−liquid equilibria of sulfanilic acid in different organic solvents are essential for industrial design and further theoretical studies. In this study, the solubilities of sulfanilic acid were measured in methanol, ethanol, 2-propanol, acetone, acetonitrile, formic acid, and acetic acid with the temperature range of (278.15 to 328.15) K by the analytical stirred-flask method under atmospheric pressure. For the temperature range investigated, the solubility of sulfanilic acid in the solvents increased with increasing temperature. The thermodynamic models, such as the van't Hoff model, the modified Apelblat model, and the Buchowski−Ksiazaczak λh model were investigated to describe the experimental data. It was found that the modified Apelblat model was the most suitable for predicting the solubility behavior of sulfanilic acid with increasing temperature. The calculated thermodynamic parameters indicated that in each studied solvent the dissolution process of sulfanilic acid is endothermic.

Measurement and Correlation of the Solubility of Vanillic Acid in Eight Pure and Water + Ethanol Mixed Solvents at Temperatures from (293.15 to 323.15) K

“…Subsequently, the supernatant was taken (syringe, the volume is 5 mL) and filtered (vacuum filtration, the pore size of filter membrane is 0.22 μm), and the filtrate was poured into an evaporating dish, which had been preweighed by an analytical balance (Sartorius CP124S, Germany) with an accuracy of ±0.0001 g. The solution (4–5 mL) was transferred into the preweighed evaporating dish and weighted immediately, and then the samples were dried in vacuum drying oven (Tianjin Taisite Instrument Co., Ltd.) at 318.15 K and weighted every 2 h until reaching constant weight . All experiments were repeated three times to obtain the mean values . The mole fraction solubility of vanillic acid ( x 1 ) in pure solvents was calculated by eq where m 1 and m 2 are the mass of vanillic acid and the solvent, respectively; M 1 and M 2 are the respective molar mass.…”

“…10 All experiments were repeated three times to obtain the mean values. 11 The mole fraction solubility of vanillic acid (x 1 ) in pure solvents was calculated by eq 1 12 ■ RESULTS AND DISCUSSION Thermodynamic Properties. The melting temperature T m and the heat of fusion Δ fus H of vanillic acid are 484.9 K and 32.8 kJ•mol −1 , corresponding to the literature data of 485.15 K and 29.1 kJ•mol −1 , respectively.…”